Addresses the problem of engaging and retaining parents in interventions aimed at promoting parenting effectiveness and child coping-competence in preschoolers, as a means of interrupting developmental trajectories that can lead to serious youth violence before these trajectories become stable. Focus on preschoolers reflects the fact that parents play a critical role in fostering competence in young children, but are often reluctant to engage and participate fully in well-validated preventive programs. The program to be offered is a group intervention for parents of 4- and 5-year old children attending preschools and daycare centers serving mainly families with high socioeconomic disadvantage. It emphasizes parental socialization practices that promote child coping-competence, reduce early aggression and antisocial behavior, and prepare children for the challenges of formal schooling. Intervention is held constant in a design that tests the impact of host-organization investment and involvement (H-OII) on engagement and retention (with matched random assignment of centers to experimental and control conditions). Participants-to be recruited through the Indiana Minority Health Coalition and consisting of minority and non- minority families-are exposed to a high or a low level of H-OII, which is the experimentally manipulated independent variable. This variable is deployed in two studies. Study One examines engagement and retention as a function of high vs. low levels of H-OII and evaluates short-term impact of the intervention. Study Two is a replication of the H-OII test on engagement and retention. The design integrates organizational, family, and parent-child levels of intervention and analysis to: l) test the impact of H-OII on engagement and retention in the program; 2) test a conceptual model of engagement and retention; 3) evaluate the short-term impact of the program on parenting practices and on child coping-competence and early aggression and antisocial behavior, and assess the extent to which engagement and retention are related to these outcomes; 4) explore the potential impact of H-OII on the organizational practices of centers participating in the project; and 5) refine a set of engagement and retention procedures to promote large scale evaluation and dissemination of effective programs for parents on the basis of experimental evidence on engagement and retention.